Improvement in processes for tanning



UNITED STATES PATENT QFFICE.

JAMES DAVIS AND JOHN ARMSTRONG, OF PITTSTON, PENNSYLVANIA.

IMPROVEMENT IN PROCESSES FOR TANNING.

Specification forming part of Letters Patent No. 138,138, dated April22, 1873 yapplication filed April 4, 1873.

To all whom it may concern:

Be it known that we, JAMEsDAVIs and JOHN ARMSTRONG, of Pittston, in thecounty of Luzerne and in the State of Pennsylvania, have inventedcertain new and useful Improvements in Process for Preparing Hides andSkins for Tanning; and do hereby declare that the following is a full,clear, and exact description thereof.

The nature of our invention consists in preparing hides and skins fortanning by immersing them in certain liquid compounds, as will behereinafter more fully set forth.

After hides have been limed and bated, and before the application of thetannin g-extracts, we place one hundred sides-or, say, about threethousand pounds of green salted hides or skins-in a vat containingtwenty barrels of water mixed with thirty pounds of sulphur ic acid, andlet the hides remain in the same for about half an hour. After the hideshave remained in this vat for about the specified time they aretransferred toanother vat containing twenty barrels of water,seventy-two pounds of salt, and six pounds of alum, and the hides areallowed to remain in the same for about twenty-four hours, when they areto be removed, and may be put into the tanningliquor, and treated in theusual manner for tanning leather.

In place of using two separate vats, each with a different compound, wemay place the hides in one vat only, containing twenty barrels of water,thirty pounds sulphuric acid,

seventy-two pounds of salt, and six pounds of alum, making a combinedsolution in which the hides or skins are to remain twenty-four hours,and then taken out and tanned in the usual manner. This latter bath. iskept renewed and fit for a second or any subsequent charge by addingwater to make up for loss of quantity, and also adding fifty pounds ofsalt, twenty pounds sulphuric acid, and four pounds of alum; and by thusreplenishing it may run on indefinitely.

By preparing the hides or skins in this manner before tanning they aremade perfectly clean and bleached, and rendered soft and pliable withoutany brittleness. Strong tannin gliquors may be used without inj ury tothe leather, and thereby considerable time saved. Tanning-liquor madefrom hemlock bark will, after having prepared thehides by our process,make the leather equally as good as if liquor of oak bark had beenemployed.

We do not confine ourselves to the precise proportions of theingredients herein mentioned, as they may perhaps be varied according tocircumstances.

We are fully aware that the ingredients herein described are well known,and have long been used in tanning; hence we disclaim such as ourinvention.

What we claim, is-

The described process of tanning, consisting in the application of thecompound described to the hides and skins after liming and hating, andbefore the introduction of tannin gextracts, as described, and for thepurposes set forth.

In testimony that we claim the foregoing we have hereunto set our handsthis 24th day of March, 1873.

JAMES DAVIS. JOHN ARMSTRONG.

Witnesses 7 JOHN VALREY, L. B. ENsIeN.

